1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) device, and more particularly, to an LCD device using a dimming control method and a driving method thereof.
2. Discussion of the Related Art
LCD devices are light and thin, and are driven with low consumption power. Due to such features, the application of LCD devices is increasingly broadened. Therefore, LCD devices are being applied to office automation equipment, audio/video equipment, portable computers such as notebook computers, etc.
Generally, in LCD devices, the amount of transmitted light is controlled according to a plurality of image signals respectively applied to a plurality of control switching elements that are arranged in a matrix type, and thus, a desired image is displayed on a screen.
LCD devices include a liquid crystal panel having a color filter substrate that is an upper substrate, a thin film transistor array substrate that is a lower substrate and a liquid crystal layer that is formed of liquid crystal filled between the upper substrate and the lower substrate, and a driver that supplies a scan signal and image information to the liquid crystal panel to drive the liquid crystal panel.
In LCD devices having the above-described configuration, consumers' demand for a model with minimized consumption power is recently increasing, and thus, various methods for minimizing consumption power are being proposed.
Among the various methods for minimizing consumption power, as a widely-used method, there is a dimming control method that controls the lighting time or light emission luminance of a backlight unit that consumes large power in driving an LCD device.
The dimming control method is categorized into a linear dimming control method and a burst dimming control method. The linear dimming control method is a method that adjusts the size of an input current (i.e., the amplitude level of the input current) that is supplied to a light source (lamp) of a backlight unit. The burst dimming control method is a method that adjusts an interval (i.e., the amplitude level of an input current) between the turn-on time and turn-off time of a light source (lamp) of a backlight unit.
Moreover, the dimming control method is categorized into a local dimming control method and a global dimming control method. The local dimming control method is a method that adjusts the brightness of a light source in units of a block according to image data. The global dimming control method is a method that turns on/off a light source overall according to image data.
FIG. 1 is a graph showing a relationship between luminance and time in applying a related art local dimming control method.
As described above, the local dimming control method is a method that repeatedly turns on/off a light source of a backlight unit in units of a block according to image data.
However, flicker is shown when the light source of the backlight unit is rapidly changed according to image data, and thus, a temporal filter algorithm that allows the light source to be slowly changed is being implemented recently.
As shown in FIG. 1, a temporal filter operates when a screen is changed from a dark screen to a bright screen or from a bright screen to a dark screen, and thus, the luminance of the backlight unit varies with time. Therefore, as shown in FIG. 1, a related art LCD device is implemented such that a time (a) taken while the luminance of the backlight unit rises is almost equal to a time (b) taken while the luminance of the backlight unit falls.
That is, by applying the local dimming control method, the related art LCD device is configured such that a time taken in turning off the backlight unit is almost equal to a time taken in turning on the backlight unit.
However, in the related art LCD device, the turn-off time of the backlight unit is the same as the turn-on time of the backlight unit, and thus, a power reduction effect due to dimming cannot be maximized.